Problem: $\left(-10x + 1\right)\left(-4x - 10\right) = \ ?$
Answer: $= -10x \cdot \left(-4x - 10\right) + 1 \cdot \left(-4x - 10\right)$ $= \left( -10x \cdot -4x \right) + \left( -10x \cdot -10 \right) + \left( 1 \cdot -4x \right) + \left( 1 \cdot -10 \right)$ $= 40x^2 + \left( -10x \cdot -10 \right) + \left( 1 \cdot -4x \right) + \left( 1 \cdot -10 \right)$ $= 40x^2 + \left( 100x - 4x \right) + \left( 1 \cdot -10 \right)$ $= 40x^2 + 96x + \left( 1 \cdot -10 \right)$ $= 40x^2 + 96x - 10$